Drilling a 2.5-kilometres-deep heat well is estimated to take about four months, and the plant is likely to take about eight months in all to build. The geothermal plant takes up little space: only a building the size of a shipping container, housing the heat pump, will be visible above ground. The Ruskeasuo geothermal plant will produce 1.8 GWh of carbon-neutral district heat per year, as well as 0.8 GWh of district cooling. The volume corresponds to the heating of about 180 apartment block homes.
"Geothermal heat is an interesting option for carbon-neutral heating. It is very challenging at the drilling stage for reasons related to drilling technology and bedrock type, which is why we have invested in seismic reflection surveying and drilling equipment. We make use of solid Finnish expertise in drilling heat wells because drilling always involves risks," says Sami Mustonen, Head of Project Management at Helen.
At a depth of two-and-a-half kilometres the earth's temperature is about 40 degrees. Water is cycled in the heat well, and by the time it enters the heat pump the water has warmed to about 10-15 degrees. With the help of heat pumps, the water temperature is raised to suit the district heating network. At the same time as the geothermal plant produces carbon-neutral heat for the district heating network, cooling is produced for the district cooling network. Through existing district heating and cooling networks, heating and cooling will be distributed to local residents.
One hundred solar panels will be installed around the heat pump plant. Electricity generated by solar power reduces the electricity consumption of the geothermal plant.
Simultaneously with the construction of the first geothermal plant, Helen's research into more extensive utilisation of geothermal heat in Helsinki is making progress. Helen is looking into the possibility of carrying out a unique 3D-seismic reflection survey, never before conducted in Finland in urban conditions.
"Based on the research results and the experience gained from the first geothermal plant, we are planning the next geothermal projects," says the Head of Project Management Sami Mustonen from Helen.
Helen has set the target of carbon neutrality by 2035. The use of coal will be phased out in 2029 at the latest. Helen is currently building new carbon-neutral production in several locations:
In addition, several studies are underway on replacing coal, such as the utilisation of waste heat in the Kilpilahti industrial area, the large-scale utilisation of seawater heat, and the potential of small-scale nuclear power (small modular reactors or SMR).